Rare-earth-based photovoltaic cell efficient heat dissipation backboard and preparation method thereof

Abstract

The invention provides a rare-earth-based photovoltaic cell efficient heat dissipation backboard and a preparation method thereof. The heat dissipation backboard comprises a rare-earth-based PET composite material layer and a fluorine-containing layer coating the surface of the rare-earth-based PET composite material layer. The rare earth-based PET composite material is prepared from the following components in parts by mass: 60 to 80 parts of PET resin, 18 to 35 parts of functional PET master batch and 2 to 3 parts of antioxidant, the functional PET master batch is prepared from raw materials including NH2-PET resin, modified flaky lanthanum cerium oxide and a dispersing agent. According to the back plate, efficient heat dissipation of the solar cell can be achieved, and therefore the effects of improving the performance of the cell and prolonging the service life of the cell are achieved.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to a rare earth-based photovoltaic cell high-efficiency heat dissipation backboard and a preparation method thereof. Background Art

[0002] Solar cells are highly sensitive to temperature fluctuations. High temperatures significantly reduce their photoelectric conversion efficiency and lifespan. Existing interlayer cooling technologies suffer from high pressure drop, uneven heat transfer, and high energy consumption. Direct contact heat exchange technologies also require high stability of the cooling medium. While radiative cooling materials are relatively common, these materials often provide excellent cooling at night, but their effectiveness in dissipating heat under sunlight is less than ideal. High temperatures severely limit the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0003] In view of this, the present invention aims to propose a rare earth-based photovoltaic cell high-efficiency heat dissipation backboard and its preparation method to solve the heat dissipation problem of the heat dissipation backboard. The backboard has the characteristics of high thermal conductivity, high reflection and high emission, and can effectively achieve heat dissipation under sunlight. The backboard is a passive heat dissipation technology with the advantages of low cost, high stability and no additional energy consumption.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows: A rare earth-based photovoltaic cell high-efficiency heat dissipation backboard comprises a rare earth-based PET composite material layer and a fluorine-containing layer coated on the surface of the rare earth-based PET composite material layer; wherein the rare earth-based PET composite material comprises, by weight, 60-80 parts of PET resin, 18-35 parts of functional PET masterbatch, and 2-3 parts of antioxidant; and the functional PET masterbatch is prepared from raw materials comprising modified flaky lanthanum cerium oxide, NH2-PET resin, and a dispersant in a mass ratio of 30-40:46-60:8-14.

[0005] Directly blending flaky lanthanum cerium oxide with PET resin will cause uneven distribution of lanthanum cerium oxide and weak affinity between lanthanum cerium oxide and resin. It is necessary to modify the PET resin and flaky lanthanum cerium oxide separately. At the same time, a dispersant is added during the extrusion blending process to enhance the adhesion between lanthanum cerium oxide and PET resin, making it less likely to settle and significantly improving the dispersibility.

[0006] Further, NH2-PET resin is prepared by the following method: S11, placing 2-aminoterephthalic acid in a vacuum oven to dry; S12, adding 4A molecular sieve to ethylene glycol and soaking overnight to purify the ethylene glycol; S13, adding 2-aminoterephthalic acid, purified ethylene glycol and ethylene glycol antimony to a flask, and introducing nitrogen into the system to replace the air; S14, inserting a water separator and a stirring paddle at the mouth of the flask, and performing an oil bath, and sequentially performing esterification reaction, pre-polycondensation and final polycondensation; S15. After the reaction, the vacuum is broken with nitrogen and the melt is rapidly water-cooled to obtain NH2-PET resin.

[0007] Further, in S11, drying is performed at 120-180° C. for 2-5 hours to reduce the water content to less than 0.01%; In S12, the ethylene glycol after soaking is filtered, and after filtering, it is subjected to reduced pressure distillation at 100° C. to collect the distilled ethylene glycol; In S14, the esterification reaction temperature is 250° C. and the stirring rate is 200-350 r / min; After the amount of water collected in the water separator is greater than 6.9 g, the system pressure is slowly reduced to 5 kPa for pre-polycondensation. The oil bath temperature is adjusted to 270 ° C and the reaction is continued for 1.5-2 hours. The pressure was reduced to below 50 Pa for final polycondensation, the oil bath temperature was adjusted to 280-290°C, and the reaction lasted for 2-3 hours.

[0008] Further, the specific preparation method of NH2-PET resin is as follows: 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours to reduce the water content to less than 0.01%.

[0009] 2) Add 5-10g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100°C to collect the distilled ethylene glycol.

[0010] 3) Weigh 36 g of dry 2-aminoterephthalic acid, 14.88-19.84 g of purified ethylene glycol, and 15-17 mg of antimony glycolate into a flask. Purge the system with nitrogen to displace the air.

[0011] 4) Insert a water separator and a stirring paddle at the mouth of the flask, and place it in an oil bath at a temperature of 250°C and a stirring rate of 200-350 r / min to carry out the esterification reaction.

[0012] 5) After the amount of water collected by the water separator is greater than 6.9 g, connect the system to a vacuum pump and slowly reduce the system pressure to 5 kPa.

[0013] 6) Adjust the oil bath temperature to 270°C and continue the reaction for 1.5-2 hours for pre-polycondensation.

[0014] 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 280-290 ° C. The reaction continues for 2-3 hours to carry out the final polycondensation.

[0015] 8) After the reaction, the vacuum is broken with nitrogen and the melt is rapidly water-cooled to obtain NH2-PET resin.

[0016] Furthermore, the modified flaky lanthanum cerium oxide includes three particle sizes, namely particle size 1: 0.1-2μm, D 50 =1μm, particle size 2: 2-8μm, D 50 =5μm, particle size 3:12-18μm, D 50 =15μm; the ratio of the three particle sizes is particle size 1: particle size 2: particle size 3=1:1.5:1, and the thickness of the modified flake lanthanum cerium oxide of the three particle sizes is 20-400nm.

[0017] Furthermore, the modified flaky lanthanum cerium oxide is prepared by the following method: Ⅰ. Preparation of flaky lanthanum cerium oxide: S21, weighing cerium carbonate and lanthanum carbonate in proportion, and dissolving the lanthanum carbonate and cerium carbonate in nitric acid solution to obtain a lanthanum cerium nitrate solution; S22, mixing the lanthanum cerium nitrate solution and the surfactant solution in proportion, and then adding the ammonium oxalate solution until precipitation is complete; S23, filtering, washing and drying the precipitate to obtain lanthanum cerium oxalate powder; S24, calcining the lanthanum cerium oxalate at 600-1000° C. for 3 h to obtain a flaky lanthanum cerium oxide powder; Ⅱ. Modified flake lanthanum cerium oxide The prepared flaky lanthanum cerium oxide is modified by using a silane coupling agent.

[0018] Furthermore, in step I, in preparing the flaky lanthanum cerium oxide: In S21, the molar ratio of cerium carbonate to lanthanum carbonate is (90-9):1, and the concentration of the obtained lanthanum cerium nitrate solution is 0.2-0.8 mol / L; In S22, the surfactant is one or more of sodium oleate, polyallyl ammonium chloride, cetyltrimethylammonium bromide, and sodium lauryl sulfate, and the concentration of the surfactant is 3-20 g / L; A lanthanum cerium nitrate solution and a surfactant solution are mixed in a mass ratio of 1:(1.6-2.8). After the mixture, the lanthanum cerium nitrate solution and the surfactant solution are heated and stirred at 40-120° C., and a rotation speed of 30-100 r / min is used. The rotation speed can be controlled to obtain flaky lanthanum cerium oxide with different particle sizes. When the rotation speed is 20-40 r / min, a particle size of 3 is obtained, when the rotation speed is 50-70 r / min, a particle size of 2 is obtained, and when the rotation speed is 90-110 r / min, a particle size of 1 is obtained. The concentration of the ammonium oxalate solution is 0.36-0.89 mol / L. The ammonium oxalate solution is added until the precipitation is complete, and the reaction is continued for 2-5 hours, and then the sedimentation is carried out at room temperature for 8-24 hours.

[0019] Furthermore, the specific steps for preparing the flaky lanthanum cerium oxide are as follows: 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of (90-9):1; 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water to prepare a 0.2-0.8 mol / L lanthanum-cerium nitrate solution; 3) Dissolve a small amount of surfactant in deionized water to prepare a 3-20g / L surfactant solution; 4) Dissolve ammonium oxalate in deionized water to prepare a 0.36-0.89 mol / L ammonium oxalate solution; 5) Mix the lanthanum cerium nitrate solution and the surfactant solution in a mass ratio of 1:(1.6-2.8), pour the mixed solution into a flask, heat and stir at 40-120°C at a speed of 30-100 r / min, add ammonium oxalate solution until precipitation is complete, and continue the reaction for 2-5 hours, and then settle at room temperature for 8-24 hours; 6) filtering, washing, and drying the precipitate to obtain lanthanum cerium oxalate powder; 7) Calcine the lanthanum cerium oxalate at 600-1000° C. for 3 h to obtain flaky lanthanum cerium oxide powder.

[0020] Furthermore, step II of modifying the flaky lanthanum cerium oxide comprises the following steps: S31, mixing and stirring the flaky lanthanum cerium oxide, deionized water, ethanol and ammonia water until fully dispersed, and heating; S32, mixing ethanol and a silane coupling agent to obtain a silane coupling agent solution; S33, adding the silane coupling agent solution dropwise to the solution system obtained in step S31 for reaction, and after the reaction, allowing the system to stand and cool, centrifuge, wash, and dry.

[0021] Furthermore, the silane coupling agent is one of 3-isocyanatepropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane and 3-isocyanatepropylmethyldimethoxysilane.

[0022] Furthermore, the specific preparation method of the modified flaky lanthanum cerium oxide is: 1) Add 10g of lanthanum cerium oxide flakes, 50-80mL of deionized water, 250-400mL of ethanol, and 15-25mL of ammonia water to a flask and stir until fully dispersed. 2) Turn on the heating, the reaction temperature is 40-80℃; 3) Measure 200 mL of ethanol and add 1-2 mL of silane coupling agent to form a uniform solution; 4) After the temperature stabilizes, add the ethanol solution of the silane coupling agent to the flask and continue the reaction for 6-10 hours; 5) After the reaction, the system was allowed to stand and cool, and then centrifuged and washed with ethanol for more than 5 times. The system was placed in a vacuum oven and vacuum dried at 50°C.

[0023] Furthermore, the thickness of the rare earth-based PET composite material layer is 200-400 μm, the thickness of the fluorine-containing layer is 20-40 μm, and the material of the fluorine-containing layer is polyvinylidene fluoride; The antioxidant is one or more of antioxidant 1076, antioxidant 3114, and antioxidant 245; The dispersant is one or more of DYD-9806, GLYCOLUBE P, and AC540A.

[0024] The present invention also provides a method for preparing the rare earth-based photovoltaic cell high-efficiency heat dissipation backplane as described above, the method comprising the following steps: 1. Preparation of functional PET masterbatch The modified flaky lanthanum cerium oxide, NH2-PET resin and dispersant are mixed in a high-speed mixer to uniformly mix the components to form a blend; the blend is added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch; 2. Melt-blending PET resin, functional PET masterbatch and antioxidant, feeding into an extruder and casting on a cold drum for rapid cooling to form a rare earth-based PET composite material layer; 3. Coating polyvinylidene fluoride on both sides of the rare earth-based PET composite material layer and performing microwave curing for 10-20 minutes to form a fluorine-containing layer to obtain a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane.

[0025] Furthermore, the temperatures of the zones of the twin-screw extruder were 240, 255, 255, 270, and 270° C., the die temperature was 270° C., and the feeding rate was 300 g / min.

[0026] Compared with the prior art, the rare earth-based photovoltaic cell high-efficiency heat dissipation backplane and its preparation method described in the present invention have the following advantages: The rare earth-based photovoltaic cell high-efficiency heat dissipation backsheet described in this invention utilizes passive cooling, offering the advantages of low cost, high stability, and no additional energy consumption. Compared to conventional PET backsheets, this backsheet has higher thermal conductivity, reflectivity, and emissivity, enabling efficient heat dissipation for solar cells and increasing their output power. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 This is a schematic structural diagram of a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to an embodiment of the present invention; Figure 2 This is a side cross-sectional view of the heat dissipation evaluation system; Figure 3 Graph showing temperature variation trends for Examples and Comparative Examples.

[0028] Description of reference numerals: 1. Rare earth-based PET composite material layer; 2. Fluorine-containing layer; 3. Heat dissipation backplane; 4. Stainless steel frame; 5. Solar cell; 6. Thermal insulation foam board; 7. SMD thermocouple. DETAILED DESCRIPTION

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] The PET resin used in the following examples of the present invention is model JT-211.

[0032] The antioxidant used in the following examples of the present invention is antioxidant 1076.

[0033] Example 1 Heat dissipation back plate like Figure 1 As shown, a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane includes a rare earth-based PET composite material layer 1 and a fluorine-containing layer 2 coated on the surface of the rare earth-based PET composite material layer 1; wherein, the rare earth-based PET composite material includes, by mass, 62 parts of PET resin, 35 parts of functional PET masterbatch, and 3 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flake lanthanum cerium oxide, and a dispersant.

[0034] The method for preparing the rare earth-based photovoltaic cell high-efficiency heat dissipation backplane comprises the following steps: 1. Preparation of NH2-PET resin 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours to reduce the water content to less than 0.01%; 2) Add 10g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100°C to collect the distilled ethylene glycol; 3) Weigh 36 g of dry 2-aminoterephthalic acid, 15 g of purified ethylene glycol, and 17 mg of antimony glycolate into a flask, and introduce nitrogen into the system to replace the air. 4) Insert a water separator and a stirring paddle at the mouth of the flask, and place it in an oil bath at a temperature of 250°C and a stirring rate of 250 r / min to carry out the esterification reaction; 5) After the amount of water collected in the water separator exceeds 6.9 g, connect the system to a vacuum pump and slowly reduce the system pressure to 5 kPa; 6) Adjust the oil bath temperature to 270°C and continue the reaction for 1.5 hours to perform pre-polycondensation; 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 280°C. Continue the reaction for 2 hours to carry out the final polycondensation. 8) After the reaction, the vacuum is broken with nitrogen and the melt is rapidly water-cooled to obtain NH2-PET resin.

[0035] 2. Preparation of modified flaky lanthanum cerium oxide Ⅰ. Preparation of flaky lanthanum cerium oxide: 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of 18:1; 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water to prepare a 0.35 mol / L lanthanum-cerium nitrate solution; 3) Dissolve a small amount of surfactant sodium oleate in deionized water to prepare a 5g / L surfactant solution; 4) Dissolve ammonium oxalate in deionized water to prepare a 0.4 mol / L ammonium oxalate solution; 5) Mix the lanthanum cerium nitrate solution and the surfactant solution in a mass ratio of 1:1.8; pour the mixed solution into a flask, heat and stir at 60°C at 30 rpm; add ammonium oxalate solution until precipitation is complete, continue the reaction for 2 hours, and then let it settle at room temperature for 12 hours; 6) filtering, washing, and drying the precipitate to obtain lanthanum cerium oxalate powder; 7) Calcine lanthanum cerium oxalate at 750℃ for 3h to obtain flaky lanthanum cerium oxide powder with a particle size of 3. The particle size range is 12-18μm, D 50 = 15 μm, the thickness of the flake lanthanum cerium oxide is 250-400 nm; 8) Repeat the above steps and adjust the stirring speed in step 5) to 60r / min and 100r / min respectively, and finally obtain flaky lanthanum cerium oxide with particle size 2 and particle size 1, which are 2-8μm and D respectively.50 =5μm and 0.1-2μm, D 50 =1μm.

[0036] Ⅱ. Modified flake lanthanum cerium oxide 1) Add 10g of lanthanum cerium oxide flakes, 50mL of deionized water, 280mL of ethanol, and 15mL of ammonia water to a flask and stir until fully dispersed. 2) Turn on the heating and set the reaction temperature to 45°C; 3) Measure 200 mL of ethanol and add 2 mL of silane coupling agent 3-isocyanatepropyltrimethoxysilane to form a uniform solution; 4) After the temperature stabilizes, add the ethanol solution of the silane coupling agent to the flask and continue the reaction for 10 hours; 5) After the reaction, the system was allowed to stand and cool, and then centrifuged and washed with ethanol for more than 5 times, placed in a vacuum oven, and vacuum dried at 50° C. to obtain modified flaky lanthanum cerium oxide; 3. Preparation of functional PET masterbatch Modified flaky lanthanum cerium oxide, NH2-PET resin, and dispersant DYD-9806 are weighed in a mass ratio of 36:52:12, wherein the ratio of the three particle sizes of the modified flaky lanthanum cerium oxide is particle size 1: particle size 2: particle size 3=1:1.5:1; the modified flaky lanthanum cerium oxide, NH2-PET resin, and dispersant DYD-9806 are mixed in a high-speed mixer to uniformly mix the components to form a blend; the blend is added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch; the temperatures of the zones of the twin-screw extruder are 240, 255, 255, 270, and 270°C, the die temperature is 270°C, and the feeding rate is 300 g / min.

[0037] 4. Prepare the backplane 1) PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast on a cold drum for rapid cooling to form a rare earth-based PET composite material layer with a thickness of 350 μm; 2) Polyvinylidene fluoride was coated on both sides of the rare earth-based PET composite material layer and microwave-cured for 10 minutes to form a 25 μm thick fluorine-containing layer, ultimately obtaining a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane.

[0038] Example 2 Heat dissipation back plate like Figure 1As shown, a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane includes a rare earth-based PET composite material layer 1 and a fluorine-containing layer 2 coated on the surface of the rare earth-based PET composite material layer 1; wherein the rare earth-based PET composite material includes, by mass, 70 parts of PET resin, 28 parts of functional PET masterbatch, and 2 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flake lanthanum cerium oxide, and a dispersant.

[0039] The method for preparing the rare earth-based photovoltaic cell high-efficiency heat dissipation backplane comprises the following steps: 1. Preparation of NH2-PET resin 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours to reduce the water content to less than 0.01%; 2) Add 8g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100°C to collect the distilled ethylene glycol; 3) Weigh 36 g of dry 2-aminoterephthalic acid, 17 g of purified ethylene glycol, and 16 mg of antimony glycolate into a flask, and introduce nitrogen into the system to replace the air. 4) Insert a water separator and a stirring paddle at the mouth of the flask, and place it in an oil bath at a temperature of 250°C and a stirring rate of 300 r / min to carry out the esterification reaction; 5) After the amount of water collected in the water separator exceeds 6.9 g, connect the system to a vacuum pump and slowly reduce the system pressure to 5 kPa; 6) Adjust the oil bath temperature to 270°C and continue the reaction for 1.5 hours to perform pre-polycondensation; 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 280 ° C. The reaction continues for 2.5 hours to carry out the final polycondensation; 8) After the reaction, the vacuum is broken with nitrogen and the melt is rapidly water-cooled to obtain NH2-PET resin.

[0040] 2. Preparation of modified flaky lanthanum cerium oxide Ⅰ. Preparation of flaky lanthanum cerium oxide: 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of 12:1; 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water to prepare a 0.65 mol / L lanthanum-cerium nitrate solution; 3) Dissolve a small amount of surfactant polyallyl ammonium chloride in deionized water to prepare a 6.5 g / L surfactant solution; 4) Dissolve ammonium oxalate in deionized water to prepare a 0.65 mol / L ammonium oxalate solution; 5) Mix the lanthanum cerium nitrate solution and the surfactant solution in a mass ratio of 1:2.8; pour the mixed solution into a flask, heat and stir at 90°C at 30 rpm; add ammonium oxalate solution until precipitation is complete, continue the reaction for 4 hours, and then let it settle at room temperature for 8 hours; 6) filtering, washing, and drying the precipitate to obtain lanthanum cerium oxalate powder; 7) Calcine lanthanum cerium oxalate at 900℃ for 3h to obtain flaky lanthanum cerium oxide powder with a particle size of 3. The particle size range is 12-18μm, D 50 = 15 μm, the thickness of the lanthanum cerium oxide flakes is 150-400 nm; 8) Repeat the above steps and adjust the stirring speed in step 5) to 60r / min and 100r / min respectively, and finally obtain flaky lanthanum cerium oxide with particle size 2 and particle size 1, which are 2-8μm and D respectively. 50 =5μm and 0.1-2μm, D 50 =1μm.

[0041] Ⅱ. Modified flake lanthanum cerium oxide 1) Add 10g of lanthanum cerium oxide flakes, 70mL of deionized water, 350mL of ethanol, and 20mL of ammonia water to a flask and stir until fully dispersed. 2) Turn on the heating and set the reaction temperature to 60°C; 3) Measure 200 mL of ethanol and add 1.5 mL of silane coupling agent 3-isocyanatepropyltriethoxysilane to form a uniform solution; 4) After the temperature stabilizes, add the ethanol solution of the silane coupling agent to the flask and continue the reaction for 8.5 hours; 5) After the reaction, the system was allowed to stand and cool, and was centrifuged, washed with ethanol for more than 5 times, placed in a vacuum oven, and vacuum dried at 50° C. to obtain modified flaky lanthanum cerium oxide.

[0042] 3. Preparation of functional PET masterbatch Modified flaky lanthanum cerium oxide, NH2-PET resin, and dispersant AC540A were weighed in a mass ratio of 33:57:10, wherein the ratio of the three particle sizes of the modified flaky lanthanum cerium oxide was particle size 1: particle size 2: particle size 3 = 1:1.5:1; the modified flaky lanthanum cerium oxide, NH2-PET resin, and dispersant AC540A were mixed in a high-speed mixer to uniformly mix the components to form a blend; the blend was added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch; the temperatures of the zones of the twin-screw extruder were 240, 255, 255, 270, and 270°C, the die temperature was 270°C, and the feeding rate was 300 g / min.

[0043] 4. Prepare the backplane 1) PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast on a cold drum for rapid cooling to form a rare earth-based PET composite material layer with a thickness of 300 μm; 2) Polyvinylidene fluoride was coated on both sides of the rare earth-based PET composite material layer and microwave-cured for 20 minutes to form a 40 μm thick fluorine-containing layer, ultimately obtaining a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane.

[0044] Example 3 Heat dissipation back plate like Figure 1 As shown, a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane includes a rare earth-based PET composite material layer 1 and a fluorine-containing layer 2 coated on the surface of the rare earth-based PET composite material layer 1; wherein the rare earth-based PET composite material includes, by mass, 80 parts of PET resin, 18 parts of functional PET masterbatch, and 2 parts of antioxidant; the functional PET masterbatch is prepared from raw materials including NH2-PET resin, modified flake lanthanum cerium oxide, and a dispersant.

[0045] The method for preparing the rare earth-based photovoltaic cell high-efficiency heat dissipation backplane comprises the following steps: 1. Preparation of NH2-PET resin 1) Place 2-aminoterephthalic acid in a vacuum oven and dry it at 150°C for 3 hours to reduce the water content to less than 0.01%; 2) Add 5g of 4A molecular sieve to 100g of ethylene glycol, soak overnight, filter, and then perform vacuum distillation at 100°C to collect the distilled ethylene glycol; 3) Weigh 36 g of dry 2-aminoterephthalic acid, 19.84 g of purified ethylene glycol, and 15 mg of antimony glycolate into a flask, and introduce nitrogen into the system to replace the air. 4) Insert a water separator and a stirring paddle at the mouth of the flask, and place it in an oil bath at a temperature of 250°C and a stirring rate of 350 r / min to carry out the esterification reaction; 5) After the amount of water collected in the water separator exceeds 6.9 g, connect the system to a vacuum pump and slowly reduce the system pressure to 5 kPa; 6) Adjust the oil bath temperature to 270°C and continue the reaction for 2 hours for pre-polycondensation; 7) Continue to evacuate the system to reduce the pressure to below 50 Pa, and continue to raise the temperature to 290°C. Continue the reaction for 3 hours to carry out the final polycondensation. 8) After the reaction, the vacuum is broken with nitrogen and the melt is rapidly water-cooled to obtain NH2-PET resin.

[0046] 2. Preparation of modified flaky lanthanum cerium oxide Ⅰ. Preparation of flaky lanthanum cerium oxide: 1) Weigh cerium carbonate and lanthanum carbonate in a molar ratio of 45:1; 2) Dissolve lanthanum carbonate and cerium carbonate in nitric acid solution, add deionized water to prepare a 0.25 mol / L lanthanum-cerium nitrate solution; 3) Dissolve a small amount of surfactant polyallyl ammonium chloride in deionized water to prepare an 18 g / L surfactant solution; 4) Dissolve ammonium oxalate in deionized water to prepare a 0.88 mol / L ammonium oxalate solution; 5) Mix the lanthanum cerium nitrate solution and the surfactant solution in a mass ratio of 1:2.6; pour the mixed solution into a flask, heat and stir at 60°C at 30 rpm; add ammonium oxalate solution until precipitation is complete, continue the reaction for 4 hours, and then let it settle at room temperature for 20 hours; 6) filtering, washing, and drying the precipitate to obtain lanthanum cerium oxalate powder; 7) Calcine lanthanum cerium oxalate at 1000℃ for 3h to obtain flaky lanthanum cerium oxide powder with a particle size of 3, the particle size range is 12-18μm, D 50 = 15 μm, the thickness of the flake lanthanum cerium oxide is 250-400 nm; 8) Repeat the above steps and adjust the stirring speed in step 5) to 60r / min and 100r / min respectively, and finally obtain flaky lanthanum cerium oxide with particle size 2 and particle size 1, which are 2-8μm and D respectively. 50 =5μm and 0.1-2μm, D 50 =1μm.

[0047] Ⅱ. Modified flake lanthanum cerium oxide 1) Add 10g of lanthanum cerium oxide flakes, 80mL of deionized water, 400mL of ethanol, and 25mL of ammonia water to a flask and stir until fully dispersed. 2) Turn on the heating and set the reaction temperature to 80°C; 3) Measure 200 mL of ethanol and add 1 mL of silane coupling agent 3-isocyanatepropylmethyldimethoxysilane to form a uniform solution; 4) After the temperature stabilizes, add the ethanol solution of the silane coupling agent to the flask and continue the reaction for 6.5 hours; 5) After the reaction, the system was allowed to stand and cool, and was centrifuged, washed with ethanol for more than 5 times, placed in a vacuum oven, and vacuum dried at 50° C. to obtain modified flaky lanthanum cerium oxide.

[0048] 3. Preparation of functional PET masterbatch Modified flaky lanthanum cerium oxide, NH2-PET resin, and dispersant GLYCOLUBE P were weighed in a mass ratio of 40:48:12, wherein the ratio of the three particle sizes of the modified flaky lanthanum cerium oxide was particle size 1:particle size 2:particle size 3=1:1.5:1; the modified flaky lanthanum cerium oxide, NH2-PET resin, and dispersant GLYCOLUBE P were mixed in a high-speed mixer to uniformly mix the components to form a blend; the blend was added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch; the temperatures of the zones of the twin-screw extruder were 240, 255, 255, 270, and 270°C, the die temperature was 270°C, and the feeding rate was 300 g / min.

[0049] 4. Prepare the backplane 1) PET resin, functional PET masterbatch and antioxidant are melt-blended, fed into an extruder and cast on a cold drum for rapid cooling to form a rare earth-based PET composite material layer with a thickness of 200 μm; 2) Polyvinylidene fluoride was coated on both sides of the rare earth-based PET composite material layer and microwave-cured for 18 minutes to form a 40 μm thick fluorine-containing layer, ultimately obtaining a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane.

[0050] Comparative Example 1 The difference from Example 1 is that flaky lanthanum cerium oxide is not used. Instead, commercially available cerium oxide and lanthanum oxide are mixed in a molar ratio of 36:1 (the lanthanum-cerium atomic ratio is 18:1) as a raw material, and the mixed lanthanum cerium oxide is processed according to the particle size requirements of particle size 1, particle size 2, and particle size 3. The three obtained particle sizes are mixed with lanthanum cerium oxide of three different particle sizes according to the particle size ratio of Example 1, and the lanthanum cerium oxide is modified using the same modification method as in Example 1, and the rest is the same as in Example 1.

[0051] Comparative Example 2 The difference from Example 1 is that only flaky lanthanum cerium oxide is used and the flaky lanthanum cerium oxide is not modified. Other aspects are the same as Example 1.

[0052] Comparative Example 3 The difference from Example 1 is that the raw material NH2-PET resin of the functional PET masterbatch is replaced with ordinary PET resin, that is, the PET resin is not modified, and the rest is the same as Example 1.

[0053] Comparative Example 4 The difference from Example 1 is that no surfactant is added in the step of preparing lanthanum cerium oxide (lanthanum cerium oxide has no flaky morphology), and the rest is the same as Example 1.

[0054] Comparative Example 5 The difference from Example 1 is that the modified flaky lanthanum cerium oxide consists of only one particle size, that is, the modified flaky lanthanum cerium oxide with a particle size of 1 is used, and the rest is the same as Example 1.

[0055] Comparative Example 6 The difference from Example 1 is that the modified flaky lanthanum cerium oxide consists of only one particle size, that is, the modified flaky lanthanum cerium oxide with a particle size of 3 is used. The rest is the same as Example 1.

[0056] Comparative Example 7 The difference from Example 1 is that the ratio of the three particle sizes of the modified flaky lanthanum cerium oxide is particle size 1: particle size 2: particle size 3 = 1:1:1, and the rest is the same as Example 1.

[0057] The commercial PET back sheet was used as the control group, and the heat dissipation performance of the heat dissipation back sheets obtained in the above examples and comparative examples was evaluated. Figure 2 The heat dissipation evaluation system shown in the figure includes a heat dissipation backplate 3, a stainless steel frame 4, a solar cell 5, an insulating foam board 6, and a patch thermocouple 7. The stainless steel frame 4 is tilted at 40 degrees. The heat dissipation backplate 3 and the solar cell 5 are placed on the stainless steel frame 4 from bottom to top. The contact points between the heat dissipation backplate 3, the solar cell 5, and the stainless steel frame 4 are surrounded by an insulating foam board 6 to prevent heat conduction between them and the stainless steel frame. A patch thermocouple 7 is attached to the upper surface of the solar cell 5 to record temperature changes on the solar cell surface. This heat dissipation evaluation system was conducted under simulated light sources, which also simulated the tilt angle of outdoor solar cells.

[0058] The performance parameters of the heat dissipation backplanes of the control group, each embodiment and comparative example and the corresponding solar cell output power are shown in Table 1. The specific heat dissipation effect of the solar cell is shown in Figure 3 .

[0059] Table 1 Performance parameters of heat dissipation backplane and corresponding solar cell output power

[0060] From Table 1, we can see that the control group has the lowest thermal conductivity, reflectivity and emissivity. When used as a battery backplane, the battery output power is the lowest, that is, the heat dissipation effect is the worst. This is consistent with the Figure 3 The thermal conductivity, reflectivity and emissivity of Examples 1-3 are all high, which determines their excellent heat dissipation performance and ideal battery output power. Figure 3This is manifested as a lower battery surface temperature. Comparative Examples 1 and 4 use mixed lanthanum cerium oxide and synthetic non-flaky lanthanum cerium oxide as fillers, respectively. Their thermal conductivity and reflectivity are significantly lower than those of the examples, resulting in varying degrees of reduction in their heat dissipation effects, i.e., a significant increase in the battery surface temperature. Comparative Examples 2-3 use unmodified lanthanum cerium oxide and unmodified PET as raw materials when preparing the backplane, which will lead to a decrease in the dispersion of the filler, and thus a decrease in the thermal conductivity, reflectivity and emissivity of the backplane, and a certain increase in the battery surface temperature. Comparative Examples 5-6 use single-particle size fillers, and Comparative Example 7 uses multi-particle size fillers, but the proportions of each particle size vary, which mainly leads to a decrease in their reflectivity and a slight increase in the battery surface temperature compared to the examples.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A rare earth-based photovoltaic cell high-efficiency heat dissipation backplane, characterized by: The invention comprises a rare earth-based PET composite material layer and a fluorine-containing layer coated on the surface of the rare earth-based PET composite material layer; wherein the rare earth-based PET composite material comprises, by weight, 60-80 parts of PET resin, 18-35 parts of functional PET masterbatch, and 2-3 parts of antioxidant; and the functional PET masterbatch is prepared from raw materials comprising modified flake lanthanum cerium oxide, NH2-PET resin, and dispersant in a mass ratio of 30-40:46-60:8-14.

2. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 1, characterized in that: NH2-PET resin is prepared by the following method: S11, placing 2-aminoterephthalic acid in a vacuum oven to dry; S12, adding 4A molecular sieve to ethylene glycol and soaking overnight to purify the ethylene glycol; S13, adding 2-aminoterephthalic acid, purified ethylene glycol and ethylene glycol antimony to a flask, and introducing nitrogen into the system to replace the air; S14, inserting a water separator and a stirring paddle at the mouth of the flask, and performing an oil bath, and sequentially performing esterification reaction, pre-polycondensation and final polycondensation; S15. After the reaction, the vacuum is broken with nitrogen and the melt is rapidly water-cooled to obtain NH2-PET resin.

3. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 2, characterized in that: In S11, drying is performed at 120-180°C for 2-5 hours to reduce the water content to less than 0.01%; In S12, the ethylene glycol after soaking is filtered, and after filtering, it is subjected to reduced pressure distillation at 100° C. to collect the distilled ethylene glycol; In S14, the esterification reaction temperature is 250° C. and the stirring rate is 200-350 r / min; After the amount of water collected in the water separator is greater than 6.9 g, the system pressure is slowly reduced to 5 kPa for pre-polycondensation. The oil bath temperature is adjusted to 270 ° C and the reaction is continued for 1.5-2 hours. The pressure was reduced to below 50 Pa for final polycondensation, the oil bath temperature was adjusted to 280-290°C, and the reaction lasted for 2-3 hours.

4. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 1, characterized in that: The modified lanthanum cerium oxide flakes include three particle sizes: particle size 1: 0.1-2μm, D 50 =1μm, particle size 2: 2-8μm, D 50 =5μm, particle size 3:12-18μm, D 50 =15μm; the ratio of the three particle sizes is particle size 1: particle size 2: particle size 3=1:1.5:1, and the thickness of the modified flake lanthanum cerium oxide of the three particle sizes is 20-400nm.

5. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 1, characterized in that: The modified flaky lanthanum cerium oxide is prepared by the following method: Ⅰ. Preparation of flaky lanthanum cerium oxide: S21, weighing cerium carbonate and lanthanum carbonate in proportion, and dissolving the lanthanum carbonate and cerium carbonate in nitric acid solution to obtain a lanthanum cerium nitrate solution; S22, stirring and mixing the lanthanum cerium nitrate solution and the surfactant solution in proportion, and then adding the ammonium oxalate solution until precipitation is complete; S23, filtering, washing and drying the precipitate to obtain lanthanum cerium oxalate powder; S24, calcining the lanthanum cerium oxalate at 600-1000° C. for 3 h to obtain a flaky lanthanum cerium oxide powder; Ⅱ. Modified flake lanthanum cerium oxide The prepared flaky lanthanum cerium oxide is modified by using a silane coupling agent.

6. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 5, characterized in that: In step I, in preparing the flaky lanthanum cerium oxide: In S21, the molar ratio of cerium carbonate to lanthanum carbonate is (90-9):1, and the concentration of the obtained lanthanum cerium nitrate solution is 0.2-0.8 mol / L; In S22, the surfactant is one or more of sodium oleate, polyallyl ammonium chloride, cetyltrimethylammonium bromide, and sodium lauryl sulfate, and the concentration of the surfactant is 3-20 g / L; A lanthanum cerium nitrate solution and a surfactant solution are mixed in a mass ratio of 1:(1.6-2.8). After the mixture, the lanthanum cerium nitrate solution and the surfactant solution are heated and stirred at 40-120° C., and a rotation speed of 30-100 r / min is used. The rotation speed can be controlled to obtain flaky lanthanum cerium oxide with different particle sizes. When the rotation speed is 20-40 r / min, a particle size of 3 is obtained, when the rotation speed is 50-70 r / min, a particle size of 2 is obtained, and when the rotation speed is 90-110 r / min, a particle size of 1 is obtained. The concentration of the ammonium oxalate solution is 0.36-0.89 mol / L. The ammonium oxalate solution is added until the precipitation is complete, and the reaction is continued for 2-5 hours, and then the sedimentation is carried out at room temperature for 8-24 hours.

7. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 5, characterized in that: Step II: Modifying the flaky lanthanum cerium oxide comprises the following steps: S31, mixing and stirring the flaky lanthanum cerium oxide, deionized water, ethanol and ammonia water until fully dispersed, and heating; S32, mixing ethanol and a silane coupling agent to obtain a silane coupling agent solution; S33, adding the silane coupling agent solution dropwise to the solution system obtained in step S31 for reaction, and after the reaction, allowing the system to stand and cool, centrifuge, wash, and dry.

8. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 7, characterized in that: The silane coupling agent is one of 3-isocyanate propyl trimethoxy silane, 3-isocyanate propyl triethoxy silane and 3-isocyanate propyl methyl dimethoxy silane.

9. The rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to claim 1, characterized in that: The thickness of the rare earth-based PET composite material layer is 200-400 μm, the thickness of the fluorine-containing layer is 20-40 μm, and the material of the fluorine-containing layer is polyvinylidene fluoride; The antioxidant is one or more of antioxidant 1076, antioxidant 3114, and antioxidant 245; The dispersant is one or more of DYD-9806, GLYCOLUBE P, and AC540A.

10. A method for preparing a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane according to any one of claims 1 to 9, characterized in that: The method comprises the following steps:

1. Preparation of functional PET masterbatch The modified flaky lanthanum cerium oxide, NH2-PET resin and dispersant are mixed in a high-speed mixer to uniformly mix the components to form a blend; the blend is added to a twin-screw extruder for melt extrusion and granulation to obtain a functional PET masterbatch; 2. Melt-blending PET resin, functional PET masterbatch and antioxidant, feeding into an extruder and casting on a cold drum for rapid cooling to form a rare earth-based PET composite material layer; 3. Coating polyvinylidene fluoride on both sides of the rare earth-based PET composite material layer and performing microwave curing for 10-20 minutes to form a fluorine-containing layer to obtain a rare earth-based photovoltaic cell high-efficiency heat dissipation backplane.

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